Struct Task Copy item path

impl<T> Task<T>

pub fn detach_on_drop(self) -> JoinHandle<T> ⓘ

Returns a JoinHandle which will have detach-on-drop semantics.

impl Task<()>

pub fn detach(self)

Detach this task so that it can run independently in the background.

Note: This is usually not what you want. This API severs the control flow from the caller. This can result in flaky tests and makes it impossible to return values (including errors).

If your goal is to run multiple tasks concurrently, use Scope.

You can also use other futures combinators such as:

[futures::future::join]
[futures::future::select]
[futures::select]

or their error-aware variants

[futures::future::try_join]
[futures::future::try_select]

or their stream counterparts

[futures::stream::StreamExt::for_each]
[futures::stream::StreamExt::for_each_concurrent]
[futures::stream::TryStreamExt::try_for_each]
[futures::stream::TryStreamExt::try_for_each_concurrent]

can meet your needs.

impl<T: Send + 'static> Task<T>

pub fn spawn(future: impl Future<Output = T> + Send + 'static) -> Task<T> ⓘ

Spawn a new task on the global scope of the current executor.

The task may be executed on any thread(s) owned by the current executor. See Task::local for an equivalent that ensures locality.

The passed future will live until either (a) the future completes, (b) the returned Task is dropped while the executor is running, or (c) the executor is destroyed; whichever comes first.

Code that uses scopes is encouraged to spawn on a shorter lived scope or explicitly call Scope::global() for spawning.

§Panics

May panic if not called in the context of an executor (e.g. within a call to run).

impl<T: 'static> Task<T>

pub fn local(future: impl Future<Output = T> + 'static) -> Task<T> ⓘ

Spawn a new task on the global scope of the thread local executor.

The passed future will live until either (a) the future completes, (b) the returned Task is dropped while the executor is running, or (c) the executor is destroyed; whichever comes first.

NOTE: This is not supported with a [SendExecutor] and will cause a runtime panic. Use Task::spawn instead.

Code that uses scopes is encouraged to spawn on a shorter lived scope or explicitly call Scope::global() for spawning.

§Panics

May panic if not called in the context of an executor (e.g. within a call to run).

impl<T: 'static> Task<T>

pub fn cancel(self) -> impl Future<Output = Option<T>>

Cancel a task and returns a future that resolves once the cancellation is complete. The future can be ignored in which case the task will still be cancelled.

Trait Implementations§

impl<T: Debug> Debug for Task<T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more

impl<T> Drop for Task<T>

fn drop(&mut self)

Executes the destructor for this type. Read more

impl<T> From<JoinHandle<T>> for Task<T>

fn from(value: JoinHandle<T>) -> Self

Converts to this type from the input type.

impl<T: 'static> Future for Task<T>

type Output = T

The type of value produced on completion.

fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output>

Attempts to resolve the future to a final value, registering the current task for wakeup if the value is not yet available. Read more

Auto Trait Implementations§

impl<T> !UnwindSafe for Task<T>

Blanket Implementations§

impl<T> Any for T
where T: 'static + ?Sized,

fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more

impl<T> Borrow<T> for T
where T: ?Sized,

fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more

impl<T> BorrowMut<T> for T
where T: ?Sized,

fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more

impl<T> From<T> for T

fn from(t: T) -> T

Returns the argument unchanged.

impl<T> FutureExt for T
where T: Future + ?Sized,

fn map<U, F>(self, f: F) -> Map<Self, F>
where F: FnOnce(Self::Output) -> U, Self: Sized,

Map this future’s output to a different type, returning a new future of the resulting type. Read more

fn map_into(self) -> MapInto<Self, U>
where Self::Output: Into, Self: Sized,

Map this future’s output to a different type, returning a new future of the resulting type. Read more

fn then<Fut, F>(self, f: F) -> Then<Self, Fut, F>
where F: FnOnce(Self::Output) -> Fut, Fut: Future, Self: Sized,

Chain on a computation for when a future finished, passing the result of the future to the provided closure f. Read more

fn left_future(self) -> Either<Self, B>
where B: Future<Output = Self::Output>, Self: Sized,

Wrap this future in an Either future, making it the left-hand variant of that Either. Read more

fn right_future<A>(self) -> Either<A, Self>
where A: Future<Output = Self::Output>, Self: Sized,

Wrap this future in an Either future, making it the right-hand variant of that Either. Read more

fn into_stream(self) -> IntoStream<Self>
where Self: Sized,

Convert this future into a single element stream. Read more

fn flatten(self) -> Flatten<Self>
where Self::Output: Future, Self: Sized,

Flatten the execution of this future when the output of this future is itself another future. Read more

fn flatten_stream(self) -> FlattenStream<Self>
where Self::Output: Stream, Self: Sized,

Flatten the execution of this future when the successful result of this future is a stream. Read more

fn fuse(self) -> Fuse<Self>
where Self: Sized,

Fuse a future such that poll will never again be called once it has completed. This method can be used to turn any Future into a FusedFuture. Read more

fn inspect<F>(self, f: F) -> Inspect<Self, F>
where F: FnOnce(&Self::Output), Self: Sized,

Do something with the output of a future before passing it on. Read more

fn catch_unwind(self) -> CatchUnwind<Self>
where Self: Sized + UnwindSafe,

Catches unwinding panics while polling the future. Read more

fn shared(self) -> Shared<Self>
where Self: Sized, Self::Output: Clone,

Create a cloneable handle to this future where all handles will resolve to the same result. Read more

fn remote_handle(self) -> (Remote<Self>, RemoteHandle<Self::Output>)
where Self: Sized,

Turn this future into a future that yields () on completion and sends its output to another future on a separate task. Read more

fn boxed<'a>(self) -> Pin<Box<dyn Future<Output = Self::Output> + Send + 'a>>
where Self: Sized + Send + 'a,

Wrap the future in a Box, pinning it. Read more

fn boxed_local<'a>(self) -> Pin<Box<dyn Future<Output = Self::Output> + 'a>>
where Self: Sized + 'a,

Wrap the future in a Box, pinning it. Read more

fn unit_error(self) -> UnitError<Self>
where Self: Sized,

Turns a Future<Output = T> into a TryFuture<Ok = T, Error = ()>.

fn never_error(self) -> NeverError<Self>
where Self: Sized,

Turns a Future<Output = T> into a TryFuture<Ok = T, Error = Never>.

fn poll_unpin(&mut self, cx: &mut Context<'_>) -> Poll<Self::Output>
where Self: Unpin,

A convenience for calling Future::poll on Unpin future types.

fn now_or_never(self) -> Option<Self::Output>
where Self: Sized,

Evaluates and consumes the future, returning the resulting output if the future is ready after the first call to Future::poll. Read more

impl<T, U> Into for T
where U: From<T>,

fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

impl<F> IntoFuture for F
where F: Future,

type Output = <F as Future>::Output

The output that the future will produce on completion.

type IntoFuture = F

Which kind of future are we turning this into?

fn into_future(self) -> <F as IntoFuture>::IntoFuture

Creates a future from a value. Read more

impl<T> Pointable for T

type Init = T

The type for initializers.

unsafe fn init(init: <T as Pointable>::Init) -> usize

Initializes a with the given initializer. Read more

unsafe fn deref<'a>(ptr: usize) -> &'a T

Dereferences the given pointer. Read more

unsafe fn deref_mut<'a>(ptr: usize) -> &'a mut T

Mutably dereferences the given pointer. Read more

unsafe fn drop(ptr: usize)

Drops the object pointed to by the given pointer. Read more

impl<F> TimeoutExt for F
where F: Future,

fn on_timeout<WT, OT>(self, time: WT, on_timeout: OT) -> OnTimeout<Self, OT> ⓘ
where WT: WakeupTime, OT: FnOnce() -> Self::Output,

Wraps the future in a timeout, calling on_timeout to produce a result when the timeout occurs.

fn on_stalled<OS>( self, timeout: Duration, on_stalled: OS, ) -> OnStalled<Self, OS> ⓘ
where OS: FnOnce() -> Self::Output,

Wraps the future in a stall-guard, calling on_stalled to produce a result when the future hasn’t been otherwise polled within the timeout. This is a heuristic - spurious wakeups will keep the detection from triggering, and moving all work to external tasks or threads with force the triggering early.

impl<T, U> TryFrom for T
where U: Into<T>,

type Error = Infallible

The type returned in the event of a conversion error.

fn try_from(value: U) -> Result<T, <T as TryFrom>::Error>

Performs the conversion.

impl<F, T, E> TryFuture for F
where F: Future<Output = Result<T, E>> + ?Sized,

type Ok = T

The type of successful values yielded by this future

type Error = E

The type of failures yielded by this future

fn try_poll( self: Pin<&mut F>, cx: &mut Context<'_>, ) -> Poll<<F as Future>::Output>

Poll this TryFuture as if it were a Future. Read more

impl<Fut> TryFutureExt for Fut
where Fut: TryFuture + ?Sized,

fn flatten_sink<Item>(self) -> FlattenSink<Self, Self::Ok>
where Self::Ok: Sink<Item, Error = Self::Error>, Self: Sized,

Flattens the execution of this future when the successful result of this future is a [Sink]. Read more

fn map_ok<T, F>(self, f: F) -> MapOk<Self, F>
where F: FnOnce(Self::Ok) -> T, Self: Sized,

Maps this future’s success value to a different value. Read more

fn map_ok_or_else<T, E, F>(self, e: E, f: F) -> MapOkOrElse<Self, F, E>
where F: FnOnce(Self::Ok) -> T, E: FnOnce(Self::Error) -> T, Self: Sized,

Maps this future’s success value to a different value, and permits for error handling resulting in the same type. Read more

fn map_err<E, F>(self, f: F) -> MapErr<Self, F>
where F: FnOnce(Self::Error) -> E, Self: Sized,

Maps this future’s error value to a different value. Read more

fn err_into<E>(self) -> ErrInto<Self, E>
where Self: Sized, Self::Error: Into<E>,

Maps this future’s Error to a new error type using the Into trait. Read more

fn ok_into(self) -> OkInto<Self, U>
where Self: Sized, Self::Ok: Into,

Maps this future’s Ok to a new type using the Into trait.

fn and_then<Fut, F>(self, f: F) -> AndThen<Self, Fut, F>
where F: FnOnce(Self::Ok) -> Fut, Fut: TryFuture<Error = Self::Error>, Self: Sized,

Executes another future after this one resolves successfully. The success value is passed to a closure to create this subsequent future. Read more

fn or_else<Fut, F>(self, f: F) -> OrElse<Self, Fut, F>
where F: FnOnce(Self::Error) -> Fut, Fut: TryFuture<Ok = Self::Ok>, Self: Sized,

Executes another future if this one resolves to an error. The error value is passed to a closure to create this subsequent future. Read more

fn inspect_ok<F>(self, f: F) -> InspectOk<Self, F>
where F: FnOnce(&Self::Ok), Self: Sized,

Do something with the success value of a future before passing it on. Read more

fn inspect_err<F>(self, f: F) -> InspectErr<Self, F>
where F: FnOnce(&Self::Error), Self: Sized,

Do something with the error value of a future before passing it on. Read more

fn try_flatten(self) -> TryFlatten<Self, Self::Ok>
where Self::Ok: TryFuture<Error = Self::Error>, Self: Sized,

Flatten the execution of this future when the successful result of this future is another future. Read more

fn try_flatten_stream(self) -> TryFlattenStream<Self>
where Self::Ok: TryStream<Error = Self::Error>, Self: Sized,

Flatten the execution of this future when the successful result of this future is a stream. Read more

fn unwrap_or_else<F>(self, f: F) -> UnwrapOrElse<Self, F>
where Self: Sized, F: FnOnce(Self::Error) -> Self::Ok,

Unwraps this future’s output, producing a future with this future’s Ok type as its Output type. Read more

fn into_future(self) -> IntoFuture<Self>
where Self: Sized,

Wraps a [TryFuture] into a type that implements Future. Read more

fn try_poll_unpin( &mut self, cx: &mut Context<'_>, ) -> Poll<Result<Self::Ok, Self::Error>>
where Self: Unpin,

A convenience method for calling [TryFuture::try_poll] on Unpin future types.

impl<T, U> TryInto for T
where U: TryFrom<T>,

type Error = >::Error

The type returned in the event of a conversion error.